When the original being read is a thin sheet of paper and the inner surface of the original cover that holds the original in place is white, an image formed on the back surface of the original may be reflected off the original cover, transmitted through the original, and picked up by the image-reading device. This phenomenon is called “show-through” and results in the image data for the front surface including a transposed image of the back surface. The image-processing device described in Japanese Patent Application Publication No. 2013-70208 modifies the light intensity emitted from a light source for reading an original between a first intensity and a second intensity smaller than the first intensity; reading the image on the original at both light intensities and converting the reflected light to first image data and second image data, respectively; and creating third image data having no show-through based on the luminance difference between the first image data and second image data.